a) Field of the Invention
The invention is directed to a load-lock device for introducing substrates into a vacuum chamber, comprising a load-lock chamber with at least one opening on the input side for introducing the substrate from an atmosphere area located in front of the input-side opening into an interior space located inside the load-lock chamber, and at least one opening on the output side for connecting the interior space of the load-lock chamber to the interior space of a vacuum chamber with the intermediary of a valve; at least one vacuum door which is associated with a respective opening on the input side and which comprises a closure element which communicates with a drive device via at least one carrier rod and is adjustable by the drive device between a position in which the input-side opening is open and a position in which the input-side opening is closed and in which the closure element contacts a contact surface of the load-lock chamber.
b) Description of the Related Art
Load-lock devices of the type mentioned above are known. In particular, load-lock devices of this type are used in production plants producing semiconductors. These load-lock devices are used for introducing substrates (workpieces) from the atmosphere into the vacuum area of the installation. In semiconductor technique, these substrates are particularly wafers, e.g., silicon wafers.
Different types of conventional slide valves and plate valves are arranged between the output-side opening of the load-lock chamber and the vacuum chamber.
The load-lock chamber has a vacuum door for closing the input-side opening of the load-lock chamber. Vacuum doors of this type are known, for example, from U.S. Pat. No. 6,056,266 A or DE 196 33 798 A1. In the apparatus of the former reference, there are two piston-cylinder units by means of which an L-shaped movement sequence of the valve plate is carried out. In the apparatus of the latter reference, a housing is supported so as to be swivelable relative to the wall in which the opening is arranged. First cylindrical bore holes are formed in the housing, pneumatic pistons whose piston rods carry the valve plate being mounted therein so as to be displaceable. The valve plate is displaced by these pistons between an open position in which the opening is released and a position in which the opening is covered, but which is raised from the wall. Further, second cylindrical bore holes are provided in the housing, and pneumatic pistons serving to swivel the housing are displaceably supported in these second cylindrical bore holes. By actuating these pneumatic pistons, the housing can be swiveled, so that the valve plate is pressed against the wall and the opening is closed so as to be vacuum-tight.
Another closure device for the vacuum closure of at least one opening in a wall is known from U.S. Pat. No. 6,427,973 B1. This closure device is also suited in particular for closing and opening a plurality of slot-shaped openings. The closure plates execute L-shaped movements between their open position and their closed position.
In semiconductor technology, for example, it is often required that the substrates are contaminated by deposition of particles as little as possible while being introduced into the vacuum chamber. For this purpose, the atmosphere area in front of the input-side opening must be charged with as few particles are possible. For this purpose, the vacuum installation can be located in a cleanroom. Further, an air flow of filtered air flowing vertical to the axis of the opening on the input side is often guided through the atmosphere area located in front of the input-side opening.
In conventional load-lock devices, it is disadvantageous that the components of the vacuum door that are arranged in the area in front of the input-side opening interfere relatively severely with the laminar flow of an air flow that is guided past this area, especially by forming whirling and/or blocking which reduces the efficiency of the air flow in keeping the surfaces of the substrates clean. Also, particles are generated (by friction between two parts) by the parts of the drive device of the vacuum door moving against one another in this area and these particles can settle on the substrate. The drive device of the vacuum door usually has pneumatic piston-cylinder units. These can leak more or less extensively, so that pneumatic air charged with particles can exit and can result in disadvantageous particle deposits on the substrates.